Compositions containing expandable microspheres and an ionic compound, as well as methods of making and using the same

ABSTRACT

This invention relates to composition containing expandable microspheres and at least one ionic compound and having a zeta potential that is greater than or equal to zero mV at a pH of about 9.0 or less at an ionic strength of from 10 −6  M to 0.1M., as well as methods of making and using the composition.

This application claims the benefit of U.S. provisional application Ser.No. 60/660,703, filed Mar. 11, 2005, entitled “COMPOSITIONS CONTAININGEXPANDABLE MICROSPHERES AND AN IONIC COMPOUND, AS WELL AS METHODS OFMAKING AND USING THE SAME”, which is hereby incorporated, in itsentirety, herein by reference.

FIELD OF THE INVENTION

This invention relates to compositions containing expandablemicrospheres and at least one ionic compound and having a zeta potentialthat is greater than or equal to zero mV at a pH of about 9.0 or less atan ionic strength of from 10⁻⁶ M to 0.1M., as well as methods of makingand using the composition.

BACKGROUND OF THE INVENTION

The amount of costly cellulose fibers present in a paper substrate, inpart, determines the density of the substrate. Therefore, large amountsof costly cellulose fibers present in a paper substrate produce a moredense substrate at high cost, while low amounts of cellulose fiberspresent in a paper substrate produce a less dense substrate at low cost.Reducing the density of a coated and/or uncoated paper product, board,and/or substrate, inevitably leads to reduced production costs thereof.This is true in all paper substrate production and uses thereof. This isespecially true, for example, in paper substrates used in envelopes,folding carton, as well as other packaging, applications. Substratesused in such as envelope and packaging applications have specifiedthickness or caliper.

By reducing the density of the paper substrate at a target caliper, lesscellulose fibers are thereby required to achieve the target caliper. Inaddition to a reduction in production costs, there is a productionefficiency that is appreciated and realized when a paper substrate'sdensity is reduced. This production efficiency is due, in part, to areduction in drying requirements (e.g. time, labor, capital, etc) of thepaper substrate during production.

Examples of reducing density of the base paper substrate include the useof:

-   -   1) multi-ply machines with bulky fibers, such as BCTMP and other        mechanical fibers in the center plies of paperboard;    -   2) extended nip press sections for reducing densification during        water removal; and    -   3) alternative calendaring technologies such as hot soft        calendaring, hot steel calendaring, steam moisturization, shoe        nip calendaring, etc.        However, these potential solutions involve high capital and        costs. Thus, they may be economically infeasible.

Still further, even if the above-mentioned costly reduction in densitymethods are realized, thus producing a paper substrate having a targetcaliper, the substrate is only useful if such methodologies foster anacceptably smooth and compressible surface of the paper substrate.Presently, there are few potential low-cost solutions to reduce densityof a paper substrate having an acceptable smoothness and compressibilityso that said substrate has a significant reduction in print mottle andacceptable smoothness.

Low density coated and uncoated paper products, board, and/or substratesare highly desirable from an aesthetic and economic perspective.However, current methodologies produce substrates that have poor printand/or printability quality. Further, acceptable smoothness targets aredifficult to attain using conventional methodologies.

One methodology is to address the above problems at lower cost throughthe use of expandable microspheres in paper substrates. Thesemethodologies, in part, can be found in the following U.S. Pat. Nos.6,846,529, 6,802,938, 5,856,389, and 5,342,649 and Published PatentApplications: 20040065424, 20040052989, and 20010038893, which arehereby incorporated, in their entirety, herein by reference.

However, such microspheres are found, when applied in the papermakingprocess, to have relatively low retention in the resultant papersubstrate. As a result, the expandable microspheres are lost to thewhite water and the efficiency of the introduction of expandablemicrospheres into the resultant paper substrate is low, therebyproviding another costly solution to the above-mentioned myriad ofcostly solutions.

Accordingly, there is still a need for a less costly and more efficientsolution to reduce density, increase bulk, and retain the goodperformance characteristics such as smoothness and print mottle within apaper substrate.

SUMMARY OF THE INVENTION

One aspect of the present invention is a composition containing at leastone expandable microsphere and at least one ionic compound. In oneembodiment, the composition has a zeta potential that is greater than orequal to zero mV at a pH of about 9.0 or less at an ionic strength offrom 10⁻⁶ M to 0.1M. In another embodiment, the ionic compound is atleast one compound selected from the group consisting of an organic andinorganic ionic compound. In yet another embodiment, the ionic compoundis at least one polyorganic compound. In yet another embodiment, theionic compound is at least one polyamine compound. In yet anotherembodiment, the ionic compound is crosslinked, branched, or combinationsthereof. In yet another embodiment, ionic compound is at least onepolyethyleneimine compound. In yet another embodiment, the ioniccompound has a weight average molecular weight that is at least 600weight average molecular weight. Further embodiments relate to methodsof making and using the composition.

In another aspect, the present invention relates to a compositioncontaining at least one expandable microsphere and at least one ioniccompound. In one embodiment, the composition has a zeta potential thatis greater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M. In another embodiment, the ioniccompound is at least one compound selected from the group consisting ofan organic and inorganic ionic compound. In yet another embodiment, theionic compound is cationic. In yet another embodiment, the ioniccompound is at least one member selected from the group of alumina andsilica. In another embodiment, the ionic compound is a colloid and/orsol containing at least one member selected from the group consisting ofsilica, alumina, tin oxide, zirconia, antimony oxide, iron oxide, andrare earth metal oxides. Further embodiments relate to methods of makingand using the composition.

In another aspect, the present invention relates to a particlecontaining at least one expandable microsphere and at least one ioniccompound. In one embodiment, the composition has a zeta potential thatis greater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M. In another embodiment, theoutside surface of the at least one expandable microsphere is bound tothe ionic compound. In another embodiment, the outside surface of the atleast one expandable microsphere is non-covalently bound to the ioniccompound. In yet another embodiment, the outside surface of at least oneexpandable microsphere is anionic. In yet another embodiment, the ioniccompound is cationic. In another embodiment, the ionic compound is atleast one compound selected from the group consisting of an organic andinorganic ionic compound. In yet another embodiment, the ionic compoundis at least one polyorganic compound. In yet another embodiment, theionic compound is at least one polyamine compound. In yet anotherembodiment, the ionic compound is crosslinked, branched, or combinationsthereof. In yet another embodiment, ionic compound is at least onepolyethyleneimine compound. In yet another embodiment, the ioniccompound has a weight average molecular weight that is at least 600weight average molecular weight. Further embodiments relate to methodsof making and using the composition.

In another aspect, the present invention relates to a particlecontaining at least one expandable microsphere and at least one ioniccompound. In one embodiment, the composition has a zeta potential thatis greater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M. In another embodiment, theoutside surface of the at least one expandable microsphere is bound tothe ionic compound. In another embodiment, the outside surface of the atleast one expandable microsphere is non-covalently bound to the ioniccompound. In yet another embodiment, the outside surface of at least oneexpandable microsphere is anionic. In yet another embodiment, the ioniccompound is cationic. In another embodiment, the ionic compound is atleast one compound selected from the group consisting of an organic andinorganic ionic compound. In yet another embodiment, the ionic compoundis cationic. In yet another embodiment, the ionic compound is at leastone member selected from the group of alumina and silica. In anotherembodiment, the ionic compound is a colloid and/or sol containing atleast one member selected from the group consisting of silica, alumina,tin oxide, zirconia, antimony oxide, iron oxide, and rare earth metaloxides. Further embodiments relate to methods of making and using thecomposition.

In yet another aspect, the present invention relates to a method ofmaking the compositions by contacting the at least one expandablemicrosphere with the at least one ionic compound to form a mixture. Inyet another embodiment, the mixture may be further centrifuged to form afirst phase comprising at least one ionic compound and a second phasecomprising a particle of the present invention.

In yet another aspect, the present invention relates to a method ofmaking the composition by adsorbing at least one ionic compound to atleast one expandable microsphere.

In yet another aspect, the present invention related to a coated and/oruncoated paper and/or paperboard substrates containing and made fromand/by any of the above and/or below aspects of the invention.Therefore, in one embodiment, the composition of the present inventionmay contain a plurality of cellulose fibers.

In yet another aspect, the present invention relates to articles andpackaging made from the coated and/or uncoated paper and/or paperboardsubstrates described herein.

In yet another aspect, the present invention relates to substrates,articles and/or packaging containing from 0.1 to 5 wt % of a pluralityof expandable microspheres; wherein the substrate, article, and/orpackage has a Sheffield Smoothness of less than 250 SU as measured byTAPPI test method T 538 om-1 and a scanning 2^(nd) cyan print mottle ofnot more than 6. In one embodiment of the present invention, thesubstrate, article and/or package may be calendared. In yet anotherembodiment of the present invention, an outside surface of theexpandable microspheres is bound to an ionic compound. In yet anotherembodiment, the substrate, article, and/or package contains from 0.1 to3 wt % of a plurality of expandable microspheres. In yet anotherembodiment, the substrate, article, and/or package contains from 0.1 to2 wt % of a plurality of expandable microspheres. In yet anotherembodiment of the present invention, the substrate, article, and/orpackage contain at least one coating layer. In yet another embodiment ofthe present invention, the coating layer is made up of at least one topcoat and at least one base coat. In yet another embodiment, thesubstrate, article, and/or package has a Sheffield Smoothness that isless than 250 SU as measured by TAPPI test method T 538 om-1 and ascanning print mottle that is less than 6 after calendaring. In yetanother embodiment, the substrate, article, and/or package has a ParkerPrint Surface Smoothness of from about 1.0 to 0.5 as measured by TAPPItest method T 555 om-99.

In another aspect, the present invention relates to an article orpackage containing at least one paper or paperboard substrate where atleast one substrate contains a web of cellulose fibers and a bulkingagent. In one embodiment, the article weighs equal to or less than oneounce. In yet another embodiment, the article has a weight whosedifference from 1 ounce is an absolute value that is more than that of aconventional package having the same number of layers.

All of the above aspects and embodiments, including methods of makingand using the same are further described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Plot of print mottle of coated paper substrate vs. amountexpandable microspheres within the substrate.

FIG. 2: Plot of the particle size distributions for microspheres beforeand after adsorption of ionic compound (e.g. PEI) thereto.

FIG. 3: Plot of zeta potential of particle formed from low and highmolecular weight ionic compound (e.g. PEI) bound to expandablemicrosphere (i.e. X-100) at different mixing times and at differentionic compound to expandable microsphere weight ratios.

FIG. 4: Plot of results of Britt Jar analyses and blowing agent (i.e.isobutane) measurements as a function of ionic compound (low and highmolecular weight ionic compound (e.g. PEI)) to expandable microsphereweight ratio and mixing time.

FIG. 5: Plot of Density Reduction of paper substrates containing thecomposition and/or particle of the present invention as a function ofionic compound (low and high molecular weight ionic compound (e.g. PEI))to expandable microsphere weight ratio and mixing time.

FIG. 6: Diagrams one embodiment of the method of the present inventionin which the one embodiment of the composition of the present inventionis made.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have now discovered a less costly and moreefficient solution to reduce density, increase bulk, and retain the goodperformance characteristics such as smoothness and print mottle within apaper substrate.

The present invention may be implemented into any conventional method ofmaking paper or paperboard substrates. Examples of such can be found intextbooks such as those described in the “Handbook for pulp and papertechnologists” by G. A. Smook (1992), Angus Wilde Publications, which ishereby incorporated, in its entirety, by reference.

One embodiment of the present invention is therefore a paper orpaperboard substrate containing expandable microspheres.

The amount of the expandable microsphere can vary and will depend uponthe total weight of the substrate, or the final paper or paperboardproduct. The paper substrate may contain greater than 0.001 wt %, morepreferably greater than 0.02 wt %, most preferably greater than 0.1 wt %of expandable microspheres based on the total weight of the substrate.Further, the paper substrate may contain less than 20 wt %, morepreferably less than 10 wt %, most preferably less than 5 wt % ofexpandable microspheres based on the total weight of the substrate. Theamount of expandable microspheres may be 0.001, 0.002, 0.005, 0.01,0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0,6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0,18.0, 19.0, and 20.0 wt % based on the total weight of the substrate,and including any and all ranges and subranges therein.

The expandable microspheres may contain an expandable shell forming avoid inside thereof. The expandable shell may comprise a carbon and/orheteroatom containing compound. An example of a carbon and/orheteroatom-containing compound may be an organic polymer and/orcopolymer. The polymer and/or copolymer may be branched and/orcrosslinked.

Expandable microspheres preferably are heat expandable thermoplasticpolymeric hollow spheres containing a thermally activatable expandingagent. Examples of expandable microsphere compositions, their contents,methods of manufacture, and uses can be found, in U.S. Pat. Nos.3,615,972; 3,864,181; 4,006,273; 4,044,176; and 6,617,364 which arehereby incorporated, in their entirety, herein by reference. Furtherreference can be made to published U.S. Patent Applications:20010044477; 20030008931; 20030008932; and 20040157057, which are herebyincorporated, in their entirety, herein by reference. Such expandablemicrospheres, for example, may be prepared from polyvinylidene chloride,polyacrylonitrile, poly-alkyl methacrylates, polystyrene or vinylchloride.

While the expandable microsphere of the present invention may containany polymer and/or copolymer, the polymer preferably has a Tg, or glasstransition temperature, ranging from −150 to +180° C., preferably from50 to 150° C., most preferably from 75 to 125° C. The Tg may be −150,−140, −130, −120, −110, −100, −90, −80, −70, −60, −50, −40, −30, −20,−10, 0, 10, 20, 30, 40, 50, 60, 70, 75, 80, 85, 90, 95, 100, 105, 110,115, 120, 125, 130, 140, 150, 160, 170, and 180° C., including any andall ranges and subranges therein.

Microspheres may also contain at least one blowing agent which, uponapplication of an amount of heat energy, functions to provide internalpressure on the inside wall of the microsphere in a manner that suchpressure causes the sphere to expand. Blowing agents may be liquidsand/or gases. Further, examples of blowing agents may be selected fromlow boiling point molecules and compositions thereof. Such blowingagents may be selected from the lower alkanes such as neopentanc,neohexane, hexane, propane, butane, pentane, and mixtures and isomersthereof. Isobutane is the preferred blowing agent for polyvinylidenechloride microspheres. Suitable coated unexpanded and expandedmicrospheres are disclosed in U.S. Pat. Nos. 4,722,943 and 4,829,094,which are hereby incorporated, in their entirety, herein by reference.

The expandable microspheres of the present invention may have a meandiameter ranging from about 0.5 to 200 microns, preferably from 2 to 100microns, most preferably from 5 to 40 microns in the unexpanded state.The mean diameter may be 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40,45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, and 200 microns, including any and all ranges and subrangestherein.

Further, the expandable microspheres of the present invention may have amaximum expansion of from about 1 to 15 times, preferably from 1.5 to 10times, most preferably from 2 to 5 times the mean diameters. The maximumexpansion may be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, and 15, including any and all ranges and subranges therein.

The expandable microspheres may be negatively or positively charged.Further, the expandable microspheres may be neutral. Still further, theexpandable microspheres may be incorporated into a composition and/orparticle of the present invention that has a net zeta potential that isgreater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M.

One embodiment of the present invention is a composition or particlecontaining an expandable microsphere.

In the composition and/or particle of the present invention, theexpandable microspheres may be neutral, negatively or positivelycharged, preferably negatively charged.

Further, the composition and/or particle of the present invention maycontain expandable microspheres of the same physical characteristicsdisclosed above and below and may be incorporated into the papersubstrate according to the present invention in the same manner and thesame amounts as mentioned above and below for the expandablemicrospheres.

Another embodiment of the present invention is a composition and/orparticle containing at least one expandable microsphere and at least oneionic compound. The expandable microsphere may be positive, neutraland/or negatively charged. Further, the ionic compound may be positiveand/or negatively charged. Preferably, the ionic compound has a netcharge that is opposite than the net charge of the expandablemicrosphere. For example, if the net charge of the expandablemicrosphere is negative, then the net charge of the ionic compound maybe any net charge, but preferably has a net positive charge.

In a preferred embodiment, when the composition and/or particle of thepresent invention contains expandable microspheres and at least oneionic compound, the composition and/or particle of the present inventionhas a net zeta potential that is greater than or equal to zero mV at apH of about 9.0 or less at an ionic strength of from 10⁻⁶ M to 0.1M.Preferably, the net zeta potential is from greater than or equal to zeroto +500, preferably greater than or equal to zero to +200, morepreferably from greater than or equal to zero to +150, most preferablyfrom +20 to +130, mV at a pH of about 9.0 or less at an ionic strengthof from 10⁻⁶ M to 0.1M as measured by standard and conventional methodsof measuring zeta potential known in the analytical and physical arts,preferably methods utilizing microelectrophoresis at room temperature.

The composition and/or particle of the present invention has a net zetapotential that is 0, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 140, 150, 160,170, 180, 190, 200, 225, 250, 300, 350, 400, 450, and 500 mV, includingany and all ranges and subranges therein.

When measuring the net zeta potential of the and/or particle of thepresent invention, preferably, such potentials are measured by standardand conventional methods of measuring zeta potential known in theanalytical and physical arts, preferably methods utilizingmicroelectrophoresis at room temperature, when the pH is any pH,preferably about 9.0 or less, more preferably about 8.0 or less, mostpreferably about 7.0 or less, at an ionic strength of from 10⁻⁶ M to0.1M. The pH may be at or about 9.0, 8.5, 8.0, 7.5, 7.0, 6.5, 6.0, 5.5,5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, and 0.5, including any andall ranges and subranges therein.

When measuring the net zeta potential of the composition and/or particleof the present invention, preferably, such potentials are measured bystandard and conventional methods of measuring zeta potential known inthe analytical and physical arts, preferably methods utilizingmicroelectrophoresis at room temperature, when the pH is about 9.0 orless, preferably about 8.0 or less, most preferably about 7.0 or less,at any ionic strength, preferably from 10⁻⁶ M to 10⁻¹ M. The ionicstrength may be 10⁻⁶, 10⁻⁵, 10⁻⁴, 10⁻³, 10⁻², and 10⁻¹ M, including anyand all ranges and subranges therein.

The ionic compound may be anionic and/or cationic, preferably cationicwhen the expandable microspheres are anionic. Further, the ioniccompound may be organic, inorganic, and/or mixtures of both. Stillfurther, the ionic compound may be in the form of a slurry and/orcolloid. Finally, the ionic compound may have a particle size ranging 1nm to 1 micron, preferably from 2 nm to 400 nm. The ionic compound mayhave a particle size that is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20,25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150,175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 450, 500, 600, 700,800, 900, and 1000 nm, where 1000 nm equals 1 micron, including any andall ranges and subranges therein.

The ionic compound may be any of the optional substances andconventional additives mentioned below and/or commonly known in the artof papermaking. More preferably, the ionic compound may be any one orcombination of the retention aids mentioned below.

The weight ratio of ionic compound to expandable microsphere in thecomposition and/or particle of the present invention may be from 1:500to 500:1, preferably from 1:50 to 50:1, more preferably from 1:10 to10:1, so long as the composition and/or particle has a net zetapotential that is greater than or equal to zero mV at a pH of about 9.0or less at an ionic strength of from 10⁻⁶ M to 0.1M. The ioniccompound/expandable microsphere weight ratio may be 1:500, 1:400, 1:300,1:200, 1:100, 1:50, 1:40, 1:30, 1:20, 1:10, 1:5, 1:1, 5:1, 10:1, 20:1,30:1, 40:1, 50:1, 100:1, 200:1, 300:1, 400:1, and 500:1, including anyand all ranges and subranges therein.

The ionic compound may be inorganic. Examples of the inorganic ioniccompound may contain, but are not limited to silica, alumina, tin oxide,zirconia, antimony oxide, iron oxide, and rare earth metal oxides. Theinorganic may preferably be in the form of a slurry and/or colloidand/or sol when contacted with the expandable microsphere and have aparticle size ranging from 1 nm to 1 micron, preferably from 2 nm to 400micron. When the inorganic ionic compound is in the form of a colloidand/or sol, the preferred ionic compound contains silica and/or alumina.

The ionic compound may be organic. Examples of the ionic organiccompound may be carbon-containing compounds. Further, the ionic organiccompound may contain heteroatoms such as nitrogen, oxygen, and/orhalogen. Still further, the ionic organic compound may contain aheteroatom-containing functional group such as hydroxy, amine, amide,carbony, carboxy, etc groups. Further the ionic organic compound maycontain more that one positive charge, negative charge, or mixturesthereof. The ionic organic compound may be polymeric and/or copolymeric,which may further by cyclic, branched and/or crosslinked. When the ionicorganic compound is polymeric and/or copolymeric, the compoundpreferably has a weight average molecular weight of from 600 to5,000,000, more preferably from 1000 to 2,000,000, most preferably from20,000 to 800,000, weight average molecular weight. The weight averagemolecular weight of the ionic compound may be 600; 700; 800; 900; 1000;2000; 3000; 4000; 5000; 7500; 10,000; 15,000; 20,000; 25,000; 30,000;40,000; 50,000; 60,000; 70,000; 80,000; 90,000; 100,000; 200,000;300,000, 400,000; 500,000; 600,000; 700,000; 800,000; 900,000;1,000,000; 1,250,000; 1,500,000; 1,750,000; 2,000,000; 3,000,000;4,000,000; and 5,000,000; including any and all ranges and subrangestherein.

Preferably, the ionic organic compound may be an amine containingcompound. More preferably, the ionic organic compound may be apolyamine. Examples include, but are not limited to, a poly(DADMAC),poly(vinylamine), and/or a poly(ethylene imine).

The composition and/or particle of the present invention may contain atleast one expandable microsphere and at least one ionic compound. Theexpandable microsphere and the ionic compound may be in contact witheach other. For example, the ionic compound is in contact with the outerand/or inner surface of the expandable microsphere. Preferably, theionic compound is in contact with the outer surface of the expandablemicrosphere. Such contact may include, but is not limited to, situationswhere the expandable microsphere is coated and/or impregnated with theionic compound. While not wishing to be bound by theory, the ioniccompound is bonded to the outside surface of the expandable microsphereby covalent and/or non-covalent forces, preferably non-covalent forces,to form a particle having an inner expandable microsphere and outerionic compound layered thereon. However, portions of the outer surfaceof the expandable microsphere layer may not be completely covered by theouter ionic compound layer, while other portions of the outer surface ofthe expandable microsphere layer may actually be completely covered bythe outer ionic compound layer. This may lead to some portions of theouter surface of the expandable microsphere layer being exposed.Further, the outside surface of the expandable microsphere may becompletely covered by a layer containing at least one ionic compound.

The composition and/or particle of the present invention may be made bycontacting, mixing, absorbing, adsorbing, etc, the expandablemicrosphere with the ionic compound. The relative amounts of expandablemicrosphere and ionic compound may be tailored by traditional means.Preferably, the relative amounts of expandable microsphere and ioniccompound may be tailored in a manner so that the resultant compositionand/or particle of the present invention has a net zeta potential thatis greater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M. Preferably, the weight ratio ofionic compound contacted with the expandable microsphere in thecomposition and/or particle of the present invention may be from 1:100to 100:1, preferably from 1:80 to 80:1, more preferably from 1:1 to1:60, most preferably from 1:2 to 1:50, so long as the compositionand/or particle has a net zeta potential that is greater than or equalto zero mV at a pH of about 9.0 or less at an ionic strength of from10⁻⁶ M to 0.1M. The weight ratio of ionic compound contacted with theexpandable microsphere in the composition and/or particle of the presentinvention may be 1:100, 1:90, 1:80, 1:70, 1:60, 1:50, 1:40, 1:30, 1:20,1:10, 1:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, and100:1, including any and all ranges and subranges therein.

The amount of contact time between the ionic compound and the expandablemicrosphere can vary from milliseconds to years just as long as theresultant composition and/or particle has a net zeta potential that isgreater than or equal to zero mV at a pH of about 9.0 or less at anionic strength of from 10⁻⁶ M to 0.1M. Preferably, the contacting occursfrom 0.01 second to 1 year, preferably from 0.1 second to 6 months, morepreferably from 0.2 seconds to 3 weeks, most preferably from 0.5 secondsto 1 week.

Prior to contacting the expandable microsphere with the ionic compound,each of the expandable microsphere and/or the ionic compound may be dryand/or in a slurry, wet cake, solid, liquid, dispersion, colloid, gel,respectively. Further, each of the expandable microsphere and/or theionic compound may be diluted and/or in concentrate.

The composition and/or particle of the present invention may have a meandiameter ranging from about 0.5 to 200 microns, preferably from 2 to 100microns, most preferably from 5 to 40 microns in the unexpanded state.The mean diameter of the composition and/or particle may be 0.5, 1, 2,3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110,120, 130, 140, 150, 160, 170, 180, 190, and 200 microns, including anyand all ranges and subranges therein.

Further, the composition and/or particle of the present invention mayhave a maximum expansion of from about 1 to 15 times, preferably from1.5 to 10 times, most preferably from 2 to 5 times the mean diameters.The maximum expansion may be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, and 15, including any and all ranges andsubranges therein.

The composition and/or particle of the present invention may be madethrough the above-mentioned contacting means prior to and/or during thepapermaking process. Preferably, the expandable microsphere and theionic compound are contacted so as to produce the composition and/orparticle of the present invention and then the resultant compositionand/or particle of the present invention is subsequently and/orsimultaneously contacted with the fibers mentioned below.

When the paper substrate of the present invention contains thecomposition and/or particle of the present invention, the amount of thecomposition and/or particle of the present invention can vary and willdepend upon the total weight of the substrate, or the final paper orpaperboard product. The paper substrate may contain greater than 0.001wt %, more preferably greater than 0.02 wt %, most preferably greaterthan 0.1 wt % of the composition and/or particle of the presentinvention based on the total weight of the substrate. Further, the papersubstrate may contain less than 20 wt %, more preferably less than 10 wt%, most preferably less than 5 wt % of the composition and/or particleof the present invention based on the total weight of the substrate. Theamount of the composition and/or particle of the present invention maybe 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0,2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0,13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, and 20.0 wt % based on thetotal weight of the substrate, and including any and all ranges andsubranges therein.

The paper substrate contains a web of cellulose fibers. The papersubstrate of the present invention may contain recycled fibers and/orvirgin fibers. Recycled fibers differ from virgin fibers in that thefibers have gone through the drying process at least once. In certainembodiments, at least a portion of the cellulose/pulp fibers may beprovided from non-woody herbaceous plants including, but not limited to,kenaf, hemp, jute, flax, sisal, or abaca although legal restrictions andother considerations may make the utilization of hemp and other fibersources impractical or impossible. Either bleached or unbleached pulpfiber may be utilized in the process of this invention.

The paper substrate of the present invention may contain from 1 to 99 wt%, preferably from 5 to 95 wt % of cellulose fibers based upon the totalweight of the substrate, including 1, 5, 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 99 wt %, and including anyand all ranges and subranges therein.

Preferably, the sources of the cellulose fibers are from softwood and/orhardwood.

The paper substrate of the present invention may contain from 1 to 100wt %, preferably from 10 to 60 wt %, cellulose fibers originating fromsoftwood species based upon the total amount of cellulose fibers in thepaper substrate. This range includes 1, 2, 5, 10, 15, 20, 25, 30, 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 wt %, includingany and all ranges and subranges therein, based upon the total amount ofcellulose fibers in the paper substrate.

The paper substrate may alternatively or overlappingly contain from 0.01to 100 wt % fibers from softwood species most preferably from 10 to 60wt % based upon the total weight of the paper substrate. The papersubstrate contains not more than 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, 85, 90, 95 and 100 wt % softwood based upon the total weight ofthe paper substrate, including any and all ranges and subranges therein.

The paper substrate may contain softwood fibers from softwood speciesthat have a Canadian Standard Freeness (csf) of from 300 to 750, morepreferably from 450 to 750. This range includes 300, 310, 320, 330, 340,350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480,490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620,630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, and 750 csf,including any and all ranges and subranges therein. Canadian StandardFreeness is as measured by TAPPI T-227 standard test.

The paper substrate of the present invention may contain from 1 to 99 wt%, preferably from 30 to 90 wt %, cellulose fibers originating fromhardwood species based upon the total amount of cellulose fibers in thepaper substrate. This range includes 1, 2, 5, 10, 15, 20, 25, 30, 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 wt %, includingany and all ranges and subranges therein, based upon the total amount ofcellulose fibers in the paper substrate.

The paper substrate may alternatively or overlappingly contain from 0.01to 100 wt % fibers from hardwood species, preferably from 60 to 90 wt %based upon the total weight of the paper substrate. The paper substratecontains not more than 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, 90, 95, 99 and 100 wt % fines based upon the total weight of thepaper substrate, including any and all ranges and subranges therein.

The paper substrate may contain fibers from hardwood species that have aCanadian Standard Freeness (esf) of from 300 to 750, more preferablyfrom 450 to 750 csf. This range includes 300, 310, 320, 330, 340, 350,360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490,500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630,640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, and 750 csf,including any and all ranges and subranges therein. Canadian StandardFreeness is as measured by TAPPI T-227 standard test.

When the paper substrate contains both hardwood and softwood fibers, itis preferable that the hardwood/softwood ratio be from 0.001 to 1000,preferably from 90/10 to 30/60. This range may include 0.001, 0.002,0.005, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 15, 20, 25, 30, 35,40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500,600, 700, 800, 900, and 1000 including any and all ranges and subrangestherein and well as any ranges and subranges therein the inverse of suchratios.

Further, the softwood and/or hardwood fibers contained by the papersubstrate of the present invention may be modified by physical and/orchemical means. Examples of physical means include, but is not limitedto, electromagnetic and mechanical means. Means for electricalmodification include, but are not limited to, means involving contactingthe fibers with an electromagnetic energy source such as light and/orelectrical current. Means for mechanical modification include, but arenot limited to, means involving contacting an inanimate object with thefibers. Examples of such inanimate objects include those with sharpand/or dull edges. Such means also involve, for example, cutting,kneading, pounding, impaling, etc means.

Examples of chemical means include, but is not limited to, conventionalchemical fiber modification means including crosslinking andprecipitation of complexes thereon. Examples of such modification offibers may be, but is not limited to, those found in the following U.S.Pat. Nos. 6,592,717, 6,592,712, 6,582,557, 6,579,415, 6,579,414,6,506,282, 6,471,824, 6,361,651, 6,146,494, H1,704, 5,731,080,5,698,688, 5,698,074, 5,667,637, 5,662,773, 5,531,728, 5,443,899,5,360,420, 5,266,250, 5,209,953, 5,160,789, 5,049,235, 4,986,882,4,496,427, 4,431,481, 4,174,417, 4,166,894, 4,075,136, and 4,022,965,which are hereby incorporated, in their entirety, herein by reference.Further modification of fibers is found in U.S. Patent Application No.60/654,712 filed Feb. 19, 2005, which may include the addition ofoptical brighteners (i.e. OBAs) as discussed therein, which is herebyincorporated, in its entirety, herein by reference.

Sources of “Fines” may be found in SaveAll fibers, recirculated streams,reject streams, waste fiber streams. The amount of “fines” present inthe paper substrate can be modified by tailoring the rate at which suchstreams are added to the paper making process.

The paper substrate preferably contains a combination of hardwoodfibers, softwood fibers and “fines” fibers. “Fines” fibers are, asdiscussed above, recirculated and are typically not more that 100 μm inlength on average, preferably not more than 90 μm, more preferably notmore than 80 μm in length, and most preferably not more than 75 μm inlength. The length of the fines are preferably not more than 5, 10, 15,20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100μm in length, including any and all ranges and subranges therein.

The paper substrate contains from 0.01 to 100 wt % fines, preferablyfrom 0.01 to 50 wt %, most preferably from 0.01 to 15 wt % based uponthe total weight of the substrate. The paper substrate contains not morethan 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15,20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100wt % fines based upon the total weight of the paper, including any andall ranges and subranges therein.

The paper substrate may alternatively or overlappingly contain from 0.01to 100 wt % fines, preferably from 0.01 to 50 wt %, most preferably from0.01 to 15 wt % based upon the total weight of the fibers contained bythe paper substrate. The paper substrate contains not more than 0.01,0.05, 0.1, 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 wt % finesbased upon the total weight of the fibers contained by the papersubstrate, including any and all ranges and subranges therein.

In a preferred embodiment, any of the above-mentioned fibers may betreated so as to have a high ISO brightness. Examples of such fiberstreated in this manner include, but is not limited to, those describedin U.S. patent application Ser. No. 11/358,543, filed Feb. 21, 2006, andentitled “PULP AND PAPER HAVING INCREASED BRIGHTNESS”, which is herebyincorporated, in its entirety, herein by reference; and PCT PatentApplication Number PCT/US06/06011, filed Feb. 21, 2006, and entitled“PULP AND PAPER HAVING INCREASED BRIGHTNESS”, which is herebyincorporated, in its entirety, herein by reference.

While the pulp, fibers, and/or paper substrate may have any brightnessand/or CIE whiteness, preferably within this embodiment, such brightnessand/or CIE whiteness is as follows.

Preferably, the fiber and/or the pulp and/or paper substrate of thepresent invention may have any CIE whiteness, but preferably has a CIEwhiteness of greater than 70, more preferably greater than 100, mostpreferably greater than 125 or even greater than 150. The CIE whitenessmay be in the range of from 125 to 200, preferably from 130 to 200, mostpreferably from 150 to 200. The CIE whiteness range may be greater thanor equal to 70, 80, 90, 100, 110, 120, 125, 130, 135, 140, 145, 150,155, 160, 65, 170, 175, 180, 185, 190, 195, and 200 CIE whitenesspoints, including any and all ranges and subranges therein. Examples ofmeasuring CIE whiteness and obtaining such whiteness in a fiber andpaper made therefrom can be found, for example, in U.S. Pat. No.6,893,473, which is hereby incorporated, in its entirety, herein byreference.

The fibers, the pulp and/or paper substrate of the present invention mayhave any ISO brightness, but preferably greater than 80, more preferablygreater than 90, most preferably greater than 95 ISO brightness points.The ISO brightness may be preferably from 80 to 100, more preferablyfrom 90 to 100, most preferably from 95 to 100 ISO brightness points.This range include greater than or equal to 80, 85, 90, 91, 92, 93, 94,95, 96, 97, 98, 99, and 100 ISO brightness points, including any and allranges and subranges therein. Examples of measuring ISO brightness andobtaining such brightness in a papermaking fiber and paper madetherefrom can be found, for example, in U.S. Pat. No. 6,893,473, whichis hereby incorporated, in its entirety, herein by reference.

The paper substrate of the present invention may have a pH of from 1.0to 14.0, preferably 4.0 to 9.0, as measured by any conventional methodsuch as a pH marker/pen and conventional TAPPI methods 252 and 529 (hotextraction test and/or surface pH test). This range includes pH's of4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0 including anyand all ranges and subranges therein.

The paper substrate according to the present invention may be made offof the paper machine having any basis weight. The paper substrate mayhave either a high or low basis weight, including basis weights of atleast 10 lbs/3000 square foot, preferably from at least 20 to 500lbs/3000 square foot, more preferably from at least 40 to 325 lbs/3000square foot. The basis weight may be 10, 20, 30, 40, 50, 60, 70, 80, 90,100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230,240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370,380, 390, 400, 425, 450, 475, and 500 lbs/3000 square foot, includingany and all ranges and subranges therein. Of course these weights caneasily be converted so as to be based upon 1300 square foot.

The paper substrate according to the present invention may have anapparent density of from 1 to 20, preferably 4 to 14, most preferablyfrom 5 to 10, lb/3000 sq. ft. per 0.001 inch thickness. The papersubstrate may have an apparent density of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 lb/3000 sq. ft. per 0.001inch thickness, including any and all ranges and subranges therein. Ofcourse, these weights can easily be converted so as to be based upon1300 square foot.

The paper substrate according to the present invention may have acaliper of from 2 to 35 mil, preferably from 5 to 30 mil, morepreferably from 10 to 28 mil, most preferably from 12 to 24 mil. Thepaper substrate may have a caliper that is 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,29, 30, 31, 32, 33, 34, and 35 mil, including any and all ranges andsubranges therein. Any of the above-mentioned calipers of the presentinvention may be that of the paper substrate of the present inventioneither prior to or after calendaring means, such as those mentionedlater below.

The paper substrate according to the present invention may have aSheffield Smoothness of less than 400 Sheffield Units (SU). However, thepreferred Sheffield Smoothness will be driven by the end product papersubstrate's intended use. Preferably, the paper substrate according tothe present invention may have a Sheffield Smoothness of less than 350SU, more preferably less than 250 SU, most preferably less than 200 SU,as measured by TAPPI test method T 538 om-1, including any and allranges and subranges therein. The paper substrate may have a SheffieldSmoothness that is 400, 350, 300, 275, 250, 225, 200, 190, 180, 170,160, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30, 20, and10, including any and all ranges and subranges therein.

The Sheffield Smoothness of the paper substrate of the present inventionis improved by at least 1%, preferably at least 20%, more preferably byat least 30%, and most preferably by at least 50% compared to that ofconventional paper substrates not containing the expandable microspheresand/or the composition and/or particle of the present invention. TheSheffield Smoothness of the paper substrate of the present invention isimproved by 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150,175, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, and 1000%compared to that of conventional paper substrates not containing theexpandable microspheres and/or the composition and/or particle of thepresent invention.

The paper substrate of the present invention may also include optionalsubstances including retention aids, sizing agents, binders, fillers,thickeners, and preservatives. Examples of fillers include, but are notlimited to; clay, calcium carbonate, calcium sulfate hemihydrate, andcalcium sulfate dehydrate. A preferable filler is calcium carbonate withthe preferred form being precipitated calcium carbonate. Examples ofbinders include, but are not limited to, polyvinyl alcohol, Amres (aKymene type), Bayer Parez, polychloride emulsion, modified starch suchas hydroxyethyl starch, starch, polyacrylamide, modified polyacrylamide,polyol, polyol carbonyl adduct, ethanedial/polyol condensate, polyamide,epichlorohydrin, glyoxal, glyoxal urea, ethanedial, aliphaticpolyisocyanate, isocyanate, 1,6 hexamethylene diisocyanate,diisocyanate, polyisocyanate, polyester, polyester resin, polyacrylate,polyacrylate resin, acrylate, and methacrylate. Other optionalsubstances include, but are not limited to silicas such as colloidsand/or sols. Examples of silicas include, but are not limited to, sodiumsilicate and/or borosilicates. Other examples of optional substances aresolvents including but not limited to water.

The paper substrate of the present invention may contain retention aidsselected from the group consisting of coagulation agents, flocculationagents, and entrapment agents dispersed within the bulk and porosityenhancing additives cellulosic fibers.

Retention aids for the bulk-enhancing additives to retain a significantpercentage of the additive in the middle of the paperboard and not inthe periphery. Suitable retention aids function through coagulation,flocculation, or entrapment of the bulk additive. Coagulation comprisesa precipitation of initially dispersed colloidal particles. Thisprecipitation is suitably accomplished by charge neutralization orformation of high charge density patches on the particle surfaces. Sincenatural particles such as fines, fibers, clays, etc., are anionic,coagulation is advantageously accomplished by adding cationic materialsto the overall system. Such selected cationic materials suitably have ahigh charge to mass ratio. Suitable coagulants include inorganic saltssuch as alum or aluminum chloride and their polymerization products(e.g. PAC or poly aluminum chloride or synthetic polymers);poly(diallyldimethyl ammonium chloride) (i.e., DADMAC);poly(dimethylamine)-co-epichlorohydrin; polyethylenimine;poly(3-butenyltrimethyl ammoniumchloride);poly(4-ethenylbenzyltrimethylammonium chloride);poly(2,3-epoxypropyltrimethylammonium chloride);poly(5-isoprenyltrimethylammonium chloride); andpoly(acryloyloxyethyltrimethylammonium chloride). Other suitablecationic compounds having a high charge to mass ratio include allpolysulfonium compounds, such as, for example the polymer made from theadduct of 2-chloromethyl; 1,3-butadiene and a dialkylsulfide, allpolyamines made by the reaction of amines such as, for example,ethylenediamine, diethylenetriamine, triethylenetetraamine or variousdialkylamines, with bis-halo, bis-epoxy, or chlorohydrin compounds suchas, for example, 1-2 dichloroethane, 1,5-diepoxyhexane, orepichlorohydrin, all polymers of guanidine such as, for example, theproduct of guanidine and formaldehyde with or without polyamines. Thepreferred coagulant is poly(diallyldimethyl ammonium chloride) (i.e.,DADMAC) having a molecular weight of about ninety thousand to twohundred thousand and polyethylenimene having a molecular weight of aboutsix hundred to 5 million. The molecular weights of all polymers andcopolymers herein this application are based on a weight averagemolecular weight commonly used to measure molecular weights of polymericsystems.

Another advantageous retention system suitable for the manufacture ofpaperboard of this invention is flocculation. This is basically thebridging or networking of particles through oppositely charged highmolecular weight macromolecules. Alternatively, the bridging isaccomplished by employing dual polymer systems. Macromolecules usefulfor the single additive approach are cationic starches (both amylase andamylopectin), cationic polyacrylamide such as for example,poly(acrylamide)-co-diallyldimethyl ammonium chloride;poly(acrylamide)-co-acryloyloxyethyl trimethylammonium chloride,cationic gums, chitosan, and cationic polyacrylates. Naturalmacromolecules such as, for example, starches and gums, are renderedcationic usually by treating them with 2,3-epoxypropyltrimethylammoniumchloride, but other compounds can be used such as, for example,2-chloroethyl-dialkylamine, acryloyloxyethyldialkyl ammonium chloride,acrylamidoethyltrialkylammonium chloride, etc. Dual additives useful forthe dual polymer approach are any of those compounds which function ascoagulants plus a high molecular weight anionic macromolecule such as,for example, anionic starches, CMC (carboxymethylcellulose), anionicgums, anionic polyacrylamides (e.g., poly(acrylamide)-co-acrylic acid),or a finely dispersed colloidal particle (e.g., colloidal silica,colloidal alumina, bentonite clay, or polymer micro particles marketedby Cytec Industries as Polyflex). Natural macromolecules such as, forexample, cellulose, starch and gums are typically rendered anionic bytreating them with chloroacetic acid, but other methods such asphosphorylation can be employed. Suitable flocculation agents arenitrogen containing organic polymers having a molecular weight of aboutone hundred thousand to thirty million. The preferred polymers have amolecular weight of about ten to twenty million. The most preferred havea molecular weight of about twelve to eighteen million. Suitable highmolecular weight polymers are polyacrylamides, anionicacrylamide-acrylate polymers, cationic acrylamide copolymers having amolecular weight of about five hundred thousand to thirty million andpolyethylenimenes having molecular weights in the range of about fivehundred thousand to two million.

The third method for retaining the bulk additive in the fiberboard isentrapment. This is the mechanical entrapment of particles in the fibernetwork. Entrapment is suitably achieved by maximizing network formationsuch as by forming the networks in the presence of high molecular weightanionic polyacrylamides, or high molecular weight polyethyleneoxides(PEO). Alternatively, molecular nets are formed in the network by thereaction of dual additives such as, for example, PEO and a phenolicresin.

The optional substances may be dispersed throughout the cross section ofthe paper substrate or may be more concentrated within the interior ofthe cross section of the paper substrate. Further, other optionalsubstances such as binders and/or sizing agents for example may beconcentrated more highly towards the outer surfaces of the cross sectionof the paper substrate. More specifically, a majority percentage ofoptional substances such as binders or sizing agents may preferably belocated at a distance from the outside surface of the substrate that isequal to or less than 25%, more preferably 10%, of the total thicknessof the substrate. Examples of localizing such optional substances suchas binders/sizing agents as a function of the cross-section of thesubstrate is, for example, paper substrates having an “1-beam” structureand may be found in U.S. Provisional Patent Application 60/759,629,entitled “PAPER SUBSTRATES CONTAINING HIGH SURFACE SIZING AND LOWINTERNAL SIZING AND HAVING HIGH DIMENSIONAL STABILITY”, which is herebyincorporated, in its entirety, herein by reference. Further examplesthat include the addition of bulking agents may be found in U.S.Provisional Patent Application 60/759,630, entitled “PAPER SUBSTRATESCONTAINING A BULKING AGENT, HIGH SURFACE SIZING, LOW INTERNAL SIZING ANDHAVING HIGH DIMENSIONAL STABILITY”, which is hereby incorporated, in itsentirety, herein by reference; and U.S. patent application Ser. No.10/662,699, now published as publication number 2004-0065423, entitled“PAPER WITH IMPROVED STIFFNESS AND BULK AND METHOD FOR MAKING SAME”,which is hereby incorporated, in its entirety, herein by reference.

One example of a binder is polyvinyl alcohol such as polyvinyl alcoholhaving a % hydrolysis ranging from 100% to 75%. The % hydrolysis of thepolyvinyl alcohol may be 75, 76, 78, 80, 82, 84, 85, 86, 88, 90, 92, 94,95, 96, 98, and 100% hydrolysis, including any and all ranges andsubranges therein.

The paper substrate of the present invention may then contain PVOH at awt % of from 0.05 wt % to 20 wt % based on the total weight of thesubstrate. This range includes 0.001, 0.002, 0.005, 0.006, 0.008, 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 4,5, 6, 8, 10, 12, 14, 15, 16, 18, and 20 wt % based on the total weightof the substrate, including any and all ranges and subranges therein.

The paper substrate of the present invention may also contain a surfacesizing agent such as starch and/or modified and/or functionalequivalents thereof at a wt % of from 0.05 wt % to 20 wt %, preferablyfrom 5 to 15 wt % based on the total weight of the substrate. The wt %of starch contained by the substrate may be 0.05, 0.1, 0.2, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, and 20 wt% based on the total weight of the substrate, including any and allranges and subranges therein. Examples of modified starches include, forexample, oxidized, cationic, ethylated, hydroethoxylated, etc. Examplesof functional equivalents are, but not limited to, polyvinyl alcohol,polyvinylamine, alginate, carboxymethyl cellulose, etc.

The paper substrate may be made by contacting the expandablemicrospheres and/or the composition and/or particle of the presentinvention with cellulose fibers consecutively and/or simultaneously.Still further, the contacting may occur at acceptable concentrationlevels that provide the paper substrate of the present invention tocontain any of the above-mentioned amounts of cellulose and expandablemicrospheres and/or the composition and/or particle of the presentinvention isolated or in any combination thereof. More specifically, thepaper substrate of the present application may be made by adding from0.25 to 20 lbs of expandable microspheres and/or the composition and/orparticle per ton of cellulose fibers. The amount of expandablemicrospheres and/or the composition and/or particle per ton of cellulosefibers may be 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19 and 20 lbs.

The contacting may occur anytime in the papermaking process including,but not limited to the thick stock, thin stock, head box, and coaterwith the preferred addition point being at the thin stock. Furtheraddition points include machine chest, stuff box, and suction of the fanpump.

The paper substrate may be made by contacting further optionalsubstances with the cellulose fibers as well. The contacting may occuranytime in the papermaking process including, but not limited to thethick stock, thin stock, head box, size press, water box, and coater.Further addition points include machine chest, stuff box, and suction ofthe fan pump. The cellulose fibers, expandable microspheres, and/oroptional components may be contacted serially, consecutively, and/orsimultaneously in any combination with each other. The cellulose fibersand expandable microspheres may be pre-mixed in any combination beforeaddition to or during the paper-making process.

The paper substrate may be pressed in a press section containing one ormore nips. However, any pressing means commonly known in the art ofpapermaking may be utilized. The nips may be, but is not limited to,single felted, double felted, roll, and extended nip in the presses.However, any nip commonly known in the art of papermaking may beutilized.

The paper substrate may be dried in a drying section. Any drying meanscommonly known in the art of papermaking may be utilized. The dryingsection may include and contain a drying can, cylinder drying, Condebeltdrying, IR, or other drying means and mechanisms known in the art. Thepaper substrate may be dried so as to contain any selected amount ofwater. Preferably, the substrate is dried to contain less than or equalto 10% water.

The paper substrate may be passed through a size press, where any sizingmeans commonly known in the art of papermaking is acceptable. The sizepress, for example, may be a puddle mode size press (e.g. inclined,vertical, horizontal) or metered size press (e.g. blade metered, rodmetered). At the size press, sizing agents such as binders may becontacted with the substrate. Optionally these same sizing agents may beadded at the wet end of the papermaking process as needed. After sizing,the paper substrate may or may not be dried again according to theabove-mentioned exemplified means and other commonly known drying meansin the art of papermaking. The paper substrate may be dried so as tocontain any selected amount of water. Preferably, the substrate is driedto contain less than or equal to 10% water.

The paper substrate may be calendered by any commonly known calendaringmeans in the art of papermaking. More specifically, one could utilize,for example, wet stack calendering, dry stack calendering, steel nipcalendaring, hot soft calendaring or extended nip calendering, etc.While not wishing to be bound by theory, it is thought that the presenceof the expandable microspheres and/or composition and/or particle of thepresent invention may reduce and alleviate requirements for harshcalendaring means and environments for certain paper substrates,dependent on the intended use thereof. During calendaring, the substratemay be subjected to any nip pressure. However, preferably nip pressuresmay be from 5 to 50 psi, more preferably from 5 to 30 psi. The nippressure may be 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 psi, includingany and all ranges and subranges therein.

The paper substrate may be microfinished according to any microfinishingmeans commonly known in the art of papermaking. Microfinishing is ameans involving frictional processes to finish surfaces of the papersubstrate. The paper substrate may be microfinished with or without acalendering means applied thereto consecutively and/or simultaneously.Examples of microfinishing means can be found in United States PublishedPatent Application 20040123966 and references cited therein, which areall hereby, in their entirety, herein incorporated by reference.

In one embodiment of the present invention, the paper substrate of thepresent invention may be a coated paper substrate. Accordingly in thisembodiment, the paper board and/or substrate of the present inventionmay also contain at least one coating layer, including optionally twocoating layers and/or a plurality thereof. The coating layer may beapplied to at least one surface of the paper board and/or substrate,including two surfaces. Further, the coating layer may penetrate thepaper board and/or substrate. The coating layer may contain a binder.Further the coating layer may also optionally contain a pigment. Otheroptional ingredients of the coating layer are surfactants, dispersionaids, and other conventional additives for printing compositions.

The coating layer may contain a coating polymer and/or copolymer whichmay be branched and/or crosslinked. Polymers and copolymers suitable forthis purpose are polymers having a melting point below 270° C. and aglass transition temperature (Tg) in the range of −150 to +120° C. Thepolymers and copolymers contain carbon and/or heteroatoms. Examples ofsuitable polymers may be polyolefins such as polyethylene andpolypropylene, nitrocellulose, polyethylene terephthalate, Saran andstyrene acrylic acid copolymers. Representative coating polymers includemethyl cellulose, carboxymethyl cellulose acetate copolymer, vinylacetate copolymer, styrene butadiene copolymer, and styrene-acryliccopolymer. Any standard paper board and/or substrate coating compositionmay be utilized such as those compositions and methods discussed in U.S.Pat. No. 6,379,497, which is hereby incorporated, in its entirety,herein by reference. However, examples of a preferred coatingcomposition that may be utilized is found in U.S. patent applicationSer. No. 10/945,306, filed Sep. 20, 2004, which is hereby incorporated,in its entirety, herein by reference.

The coating layer may include a plurality of layers or a single layerhaving any conventional thickness as needed and produced by standardmethods, especially printing methods. For example, the coating layer maycontain a basecoat layer and a topcoat layer. The basecoat layer may,for example, contain low density thermoplastic particles and optionallya first binder. The topcoat layer may, for example, contain at least onepigment and optionally a second binder which may or may not be adifferent binder than the first. The particles of the basecoat layer andthe at least one pigment of the topcoat layer may be dispersed in theirrespective binders.

The thickness of the coating layer can vary widely and any thickness canbe used. Generally, the thickness of the coating layer is from about 1.8to about 9.0 μm at a minimum, which is figured on the average densityand weight ratio of each component in a coating. The thickness of thecoating layer is preferably from about 2.7 to about 8.1 μm and morepreferably from about 3.2 to about 6.8 μm. The coating layer thicknessmay be 1.8, 2.0, 2.2, 2.5, 2.7, 3.0, 3.2, 2.5, 3.7, 4.0, 4.2, 4.5, 4.7,5.0, 5.2, 5.5, 5.7, 6.0, 6.2, 6.5, 6.7, 7.0, 7.2, 7.5, 7.7, 8.0, 8.2,8.5, 8.7, and 9.0 μm, including any and all ranges and subrangestherein.

Coat weight of the coating layer can vary widely and any conventionalcoat can be used. Basecoats are generally applied to paper substrates inan amount from about 4 to about 20 gsm. The coat weight of the basecoatis preferably from about 6 to about 18 gsm and more preferably fromabout 7 to about 15 gsm. The basecoat coat weight is 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 gsm, including any andall ranges and subranges therein.

While the coated or uncoated paper substrate may have any basis weight,in one embodiment, the coated paper substrate according to the presentinvention may have basis weights from of at least 20 lbs/3000 squarefoot, preferably from 140 to 325 lbs/3000 square foot. The coated papersubstrate may have a basis weight of 20, 40, 60, 80, 100, 120, 140, 150,160, 170, 180, 190, 200, 210, 220, 240, 250, 260, 270, 280, 290, 300,310, 320, and 325, including any and all ranges and subranges therein.

While the coated or uncoated paper substrate may have any apparentdensity, in one embodiment, the coated paper substrate according to thepresent invention may have an apparent density of from 4 to 12,preferably 5 to 10, lb/3000 sq. ft. per 0.001 inch thickness. Theapparent density of the coated paper substrate of this embodiment may be4, 5, 6, 7, 8, 9, 10, 11, and 12 lb/3000 sq. ft. per 0.001 inchthickness, including any and all ranges and subranges therein.

While the coated or uncoated paper substrate may have any apparentdensity, in one embodiment, the coated paper substrate according to thepresent invention may have a caliper of from 8 to 32 mil, preferablyfrom 12 to 24 mil. The caliper of the coated paper substrate of thisembodiment may be 8, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 26, 28, 30 and 32 mil, including any and all ranges and subrangestherein.

While the coated or uncoated paper substrate may have any SheffieldSmoothness, in one embodiment, the coated paper substrate according tothe present invention may have a Sheffield Smoothness that is less than50, preferably less than 30, more preferably less than 20, and mostpreferably less than 15 as measured by TAPPI test method T 538om-1. TheSheffield Smoothness of the coated paper substrate of this embodimentmay be 50, 45, 40, 35, 30, 25, 20, 15, 10, and 5 SU, including any andall ranges and subranges therein. The Sheffield Smoothness may prior toor after calendaring. The Sheffield Smoothness of the coated substrateof the present invention is improved by 10%, preferably 20%, morepreferably by 30%, and most preferably by 50% compared to that ofconventional coated paper substrates not containing expandablemicrospheres, the composition, and/or the particle of the presentinvention.

While the coated or uncoated paper substrate may have any Parker PrintSmoothness (10 kgf/cm²), in one embodiment, the coated paper substrateaccording to the present invention may have a Parker Print Smoothness(10 kgf/cm²) may be less than or equal to 2, preferably less than 1.5,more preferably less than 1.3, and most preferably from about 1.0 to 0.5as measured by TAPPI test method T 555 om-99. The Parker PrintSmoothness (10 kgf/cm²) of the coated paper substrate of this inventionmay be 2.0, 1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.6, 0.4 and 0.2, includingany and all ranges and subranges therein. The Parker Print Smoothness ofthe coated substrate of the present invention is improved by 5%,preferably 20%, more preferably by 30%, and most preferably by 40%compared to that of conventional coated paper substrates not containingexpandable microspheres, the composition, and/or the particle of thepresent invention. A preferred improvement in the Parker PrintSmoothness is in the range or from 10 to 20% compared to that ofconventional coated paper substrates not containing expandablemicrospheres, the composition, and/or the particle of the presentinvention.

The coated paper substrate according to the present invention may havean improved print mottle as measured by 2^(nd) Cyan scanner mottle.Scanner mottle is determined using the following procedure:Representative samples are selected from pigment coated paper orpaperboard printed under controlled conditions typical of commercialoffset litho production with the cyan process ink at a reflectiondensity of 1.35±0.05 A 100 percent solid cyan print reflective image isdigitally scanned and transformed through a neural network model toproduce a print mottle index number between zero (perfectly uniform inklay with no mottle) to ten (visually noticeable, objectionable andlikely rejectable because of print mottle, a random non-uniformity inthe visual reflective density or color of the printed area). Data fromthis 2^(nd) Cyan scanner mottle system can be correlated to subjectivevisual perception (using the zero-to-ten guideline) or can betransformed into equivalent mottle values as measured with a Tobiasmottle tester from Tobias Associates using the following equation:

Tobias=Scanner Mottle*8.8+188

The methods of describing the procedures and details of setting up ofthe above-mentioned equation can be found in U.S. patent applicationSer. No. 10/945,306, filed Sep. 20, 2004, which is hereby incorporated,in its entirety, herein by reference.

In a preferred embodiment, the coated or uncoated paper of paperboardsubstrate of the present invention has any 2^(nd) Cyan scanner printmottle. However, the 2^(nd) scanner print mottle may be from 0 to 10,preferably not more than 6, more preferably not more than 5, mostpreferably not more than 4. The 2^(nd) Cyan scanner print mottle may be1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, including any and all ranges andsubranges therein.

The print mottle of the coated substrate of the present invention isimproved by 5%, preferably 20%, more preferably by 30%, and mostpreferably by 50% compared to that of conventional coated papersubstrates not containing expandable microspheres, the composition,and/or the particle of the present invention. A preferred improvement inthe print mottle is in the range or from 10 to 20% compared to that ofconventional coated paper substrates not containing expandablemicrospheres, the composition, and/or the particle of the presentinvention. The substrate of the present invention has a 2^(nd) Cyanscanner print mottle that is improved by 1, 5, 10, 20, 30, 40, 50, 60,70, 80, 90, 100, 125, 150, 175, 200, 250, 300, 350, 400, 450, 500, 600,700, 800, 900, and 1000% compared to that of conventional coated papersubstrates not containing expandable microspheres, the composition,and/or the particle of the present invention.

In another preferred embodiment of a coating paper, a preferred exampleof the coating layer comprises a basecoat on a surface of substrate. Thebasecoat may comprise low density thermoplastic particles dispersed in apolymeric binder. As used herein, “low density thermoplastic particles”are particles formed from thermoplastic or elastic polymers having adensity of less than 1.2 Kg/Liter in a dry state including the void airvolume. The density is preferably less than 0.8 Kg/Liter, morepreferably less than 0.6 Kg/Liter and most preferably from about 0.3Kg/Liter to about 0.6 Kg/Liter. The low density thermoplastic particlespreferably are not expandable and more preferably have a diameter lessthan about 3 microns, more preferably less than about 2 micron and mostpreferably from about 0.1 to about 1.0 microns. While we do not wish tobe bound to any theory, it is believed that inclusion of the low densitythermoplastic particles makes the basecoat more compressible andenhances the beneficial properties of the material. Improved propertiesinclude reduced 2^(nd) cyan scanner mottle, enhanced sheet and printgloss and/or enhanced Sheffield and Parker Print smoothness as compareda similar material having the same characteristics except for thepresences of the low density thermoplastic particles in the basecoat.

While we do not wish to be bound by any theory, it is also believe thatthe amount of coating thickness and compressibility (range ofcompaction) load versus decrease in coating height needed to reduce backtrap offset print mottle is directly proportional to the Z-directionnon-uniformity of the base paper board's formation at offset printingpressures. For example, offset printing pressures are typically in therange of about 10 kg/sq cm that has been standardized as R (rubber) 10kg/sq cm of Parker Print Surface roughness (PPS, microns). If these loadrange is employed, the compressibility of basecoat at the employed loadrange should “float or cushion” the Z-direction hard fiber to fibercross-over points to prevent or reduce point to point printing pressurevariations. Where present, these variations lead to further variationsin ink film transfer initially and in subsequent print units thusunevenly back trapping part of the ink film to subsequent offsetblankets (impression cylinder).

Low density thermoplastic particles that can be used may vary widely andinclude, but are not limited to, hollow polymer plastic pigments andbinders having a particle size that is at least about 175 nm. Examplesof these are ROPAQUE® HP1055 and AF1353 from Rohm and Haas and the HS2000NA and HS 3000NA plastic pigments from Dow Chemical Company. Theamount of low density thermoplastic particles present in the basecoatmay vary widely but is preferably in an amount less than about 30% byweight of the basecoat composition. More preferably, they are present inan amount from about 1 to about 15% by weight of the basecoatcomposition most preferably in amount from about 2 to about 10% byweight of the basecoat composition and in amount from about 3 to about7% by weight of the basecoat composition in the embodiments of choice.

The base coat may contain a combination of calcium carbonate (orequivalent thereof) and low density thermoplastic particles. The amountof low density thermoplastic particles may be from 0.5 to 30 wt %,preferably from 1 to 8 wt %, more preferably from 3 to 7 wt %, and mostpreferably from 4 to 6 wt % based upon the combined total weight of thelow density thermoplastic particles and the calcium carbonate (orequivalent thereof).

As another essential component basecoat includes one or more polymericbinders. Illustrative of useful binders are those which areconventionally used in coated papers as for example styrene butadienerubber latex, styrene acrylate, polyvinyl alcohol and copolymers,polyvinyl acetates and copolymers, vinyl acetate copolymers,carboxylated SBR latex, styrene acrylate copolymers,styrene/butadiene/acrylonitrile,styrene/butadiene/acrylate/acrylonitrile polyvinyl pyrrolidone andcopolymers, polyethylene oxide, poly(2-ethyl-2-oxazoline, polyesterresins, gelatins, casein, alginate, cellulose derivatives, acrylic vinylpolymers, soy protein polymer, hydroxymethyl cellulose, hydroxypropylcellulose, starches, ethoxylated, oxidized and enzyme convertedstarches, cationic starches, water soluble gums, mixtures of watersoluble and water-insoluble resins or polymer latexes, and the like maybe used. Preferred polymeric binders are carboxylated SBR latexes,polyvinyl alcohol, polyvinyl acetate, styrene/acrylonitrile copolymer,styrene/butadiene copolymer, styrene/acrylate copolymer, and vinylacetate polymers and copolymers.

Binder latex particles having a sufficient particle size also provide aninitial bulking when included with inorganic or organic bulkingpigments. Latex particles in general have a particle size from about 100to about 300 nm for paper coating applications. Latex particles havingsufficient size to provide compressibility generally have a particlesize that is at least 175 nm. The size of the latex that providescompressibility is directly proportional to the average size of theinorganic and organic pigments used in basecoats. Typically, a source ofground calcium carbonate (GCC) used in paperboard basecoats isHYDROCARB® 60 (from OMYA). This ground calcium carbonate is a wet ballmilled product having 60% of its particles less than 2 microns.Conversely, 40% of the particles are equal to or larger than about 2microns. Preferably, the latex particle size is at least 175 nm forbasecoats composed mainly of HYDROCARB® 60 calcium carbonate or similarproducts. More preferably, the latex particle size is at least 185 nm,and even more preferably, the latex particle size is at least 190 nm.

The sources of calcium carbonate may be mixed at any amount. Forexample, ground calcium carbonate sources containing 60% of itsparticles less than 2 microns may be present in an amount that is from10 to 90 wt % based upon the total weight of the calcium carbonate. Theamount of calcium carbonate sources containing 60% of its particles lessthan 2 microns may be 10, 20, 30, 40, 50, 60, 70, 80, and 90 wt %, basedupon the total weight of the calcium carbonate, including any and allranges and subranges therein.

The sources of calcium carbonate may be mixed at any amount. Forexample, ground calcium carbonate sources containing 40% of itsparticles less than 2 microns may be present in an amount that is from10 to 90 wt % based upon the total weight of the calcium carbonate. Theamount of calcium carbonate sources containing 40% of its particles lessthan 2 microns may be 10, 20, 30, 40, 50, 60, 70, 80, and 90 wt %, basedupon the total weight of the calcium carbonate, including any and allranges and subranges therein.

In the more preferred embodiments of the invention, additional pigmentor fillers are employed to improve the properties of the coated paperand paperboard. These additional pigments may vary widely and includethose inorganic pigments typically used in the coated paper andpaperboard such as silica, clay, calcium sulfate, calcium silicate,activated clay, diatomaceous earth, magnesium silicate, magnesium oxide,magnesium carbonate and aluminum hydroxide. To add additional initialcoating bulk, inorganic particles such as precipitated calcium carbonatehaving bulky structures such as a rosette crystal can also be included.In the most preferred embodiments of the invention, inorganic pigmentshaving a rosette or other bulky structure can be included in thebasecoat to make the basecoat have greater initial bulk or thickness.The rosette structure provides greater coating thickness, thus improvedcoating coverage for a given coat weight. This allows for the driedcoating to more easily move in the Z-direction when compressed by thehot soft gloss calenders on coated SBS paperboard machines, and thus toform a level coated surface with a reduced number of low spots.Preferred inorganic pigments include, but are not limited to,precipitated calcium carbonate, mechanically or chemically engineeredclays, calcined clays, and other pigment types that function to lowerthe average density of the coating when dry. These pigments do notprovide compressibility to dried basecoats. They synergistically loweraverage coating density and, raise average coating thickness at a givencoat weight so compressible materials, such as larger size binders andhollow plastic spheres, become more efficient in cushioning theZ-direction non-uniformity of the base paperboard's formation fromcreating point to point variations in printing pressure in the offsetprinting nip.

Coat weight of the basecoat can vary widely and any conventional coatcan be used. Basecoats are generally applied to paper substrates in anamount from about 4 to about 20 gms. The coat weight of the basecoat ispreferably from about 6 to about 18 gms and more preferably from about 7to about 15 gms. The thickness of the basecoat can vary widely and anythickness can be used. Generally, the thickness of the basecoat is fromabout 1.8 to about 9.0 μm at a minimum, which is figured on the averagedensity and weight ratio of each component in a coating. The thicknessof the basecoat is preferably from about 2.7 to about 8.1 μm and morepreferably from about 3.2 to about 6.8 μm. When packing factors todissimilar shapes are taken into account, the average thickness whenapplied to an impervious surface would be significantly greater than thetheoretical values given here. However, because of the rough nature ofpaperboard in general and the application and metering system used toapply and meter basecoats at an average coat weight of 12 g/m², thecoating thickness at the rough high spots in the paper may be as low as2-3 microns while valleys between large surface fiber may have coatingthickness as great as 10+ microns. Stiff blade metering of the basecoatattempts to provide a level surface to which a very uniform topcoat isapplied.

An additional component of material is topcoat. Topcoat comprises one ormore inorganic pigments dispersed in one or more polymeric binders.Polymeric binders and inorganic pigments are those typically used incoatings of coated paper and paperboard. Illustrative of useful pigmentsand binders are those used in basecoat.

Coat weight of topcoat can vary widely and any conventional coat can beused. Topcoat is generally applied to paper substrates in amount fromabout 4 to about 20 gms. The coat weight of the basecoat is preferablyfrom about 6 to about 18 gms and more preferably from about 7 to about15 gms. The thickness of topcoat 16 can vary widely and any thicknesscan be used. Generally, the thickness of the basecoat is from about 1.8to about 9.0 μm at a minimum, which is figured on the average densityand weight ratio of each component in a coating. The thickness of thebasecoat is preferably from about 2.7 to about 8.1 μm and morepreferably from about 3.2 to about 6.8 μm at a minimum, which is figuredon the average density and weight ratio of each component in a coating.The point at which the void volume is filled by binder and additivesamong all pigments is referred to as the “critical void volume”. In thepaint industry this point is referred to as the transition from matte togloss paints.

The coated paper or paperboard of this invention can be prepared usingknown conventional techniques. Methods and apparatuses for forming andapplying a coating formulation to a paper substrate are well known inthe paper and paperboard art. See for example, G. A. Smook referencedabove and references cited therein all of which is hereby incorporatedby reference. All such known methods can be used in the practice of thisinvention and will not be described in detail. For example, the mixtureof essential pigments, polymeric or copolymeric binders and optionalcomponents can be dissolved or dispersed in an appropriate liquidmedium, preferably water.

The percent solids of the top and basecoat coating formulation can varywidely and conventional percent solids are used. The percent solids ofthe basecoat coating formulation is preferably from about 45% to 70%because within range excellent scanner mottle characteristics areexhibited by the material with increased drying demands. The percentsolids in the basecoat coating formulation is more preferably from about57 to 69% and is most preferably from about 60% to about 68%. Thepercent solids in the basecoat coating formulation in the embodiments ofchoice is from about 63% to 67%.

The coating formulation can be applied to the substrate by any suitabletechnique, such as cast coating, Blade coating, air knife coating, rodcoating, roll coating, gravure coating, slot-die coating, spray coating,dip coating, Meyer rod coating, reverse roll coating, extrusion coatingor the like. In addition, the coating compositions can also be appliedat the size press of a paper machine using rod metering or othermetering techniques. In the preferred embodiments of the invention, thebasecoat coating formulation is applied using blade waters and thetopcoat coating formulation is applied using a blade coater or air knifecoater. In the most preferred embodiments the basecoat is applied usinga stiff blade coater and the topcoat is applied using a bent bladecoater or an air knife coater.

The coated or uncoated paper or paperboard substrate is dried aftertreatment with the coating composition. Methods and apparatuses fordrying paper or paperboard webs treated with a coating composition arewell known in the paper and paperboard art. See for example G. A. Smookreferenced above and references cited therein. Any conventional dryingmethod and apparatus can be used. Consequently, these methods andapparatuses will not be described herein in any great detail. Preferablyafter drying the paper or paperboard web will have moisture contentequal to or less than about 10% by weight. The amount of moisture in thedried paper or paperboard web is more preferably from about 5 to about10% by weight.

After drying, the coated or uncoated paper or paperboard substrate maybe subjected to one or more post drying steps as for example thosedescribed in G. A. Smook referenced above and references cited therein.For example, the paper or paperboard web may be calendered to improvethe smoothness and improve print mottle performance, as well as otherproperties of the paper as for example by passing the coated paperthrough a nip formed by a calender. Gloss calenders (chromed steelagainst a rubber roll) or hot soft gloss calenders (chromed steelagainst a composite polymeric surface) are used to impart gloss to thetop coated paper or paperboard surface. The amount of heat and pressureneeded in these calenders depends on the speed of the web entering thenip, the roll sizes, roll composition and hardness, specific load, thetopcoat and basecoat weights, the roughness of the under lying roughpaperboard, the binder strength of the coatings, and the roughness ofthe pigments present in the coating. In general, topcoats contain veryfine particle size clays and ground or precipitate calcium carbonate,binder, rheology aids, and other additives. Typically hot soft calendersare 1 m and greater in diameter and are heated internally with very hotheat transfer fluids. The diameter of the heated steel roll is directlydependent on the width of the paper machine. In general, a wider papermachine of 400″ as compared to 300″ or 250″ wide machines requires muchlarger diameter rolls so that the weight of the roll does not causesagging of the roll in the center. Hydraulically, internally loaded,heated roils that are crown compensating are used. Surface temperaturestypically used range from 100 to 200° C. The preferable range is 130° C.to 185° C. with nip loads between 20 kN/m and 300 kN/m.

The substrate and coating layer are contacted with each other by anyconventional coating layer application means, including impregnationmeans. A preferred method of applying the coating layer is with anin-line coating process with one or more stations. The coating stationsmay be any of known coating means commonly known in the art ofpapermaking including, for example, brush, rod, air knife, spray,curtain, blade, transfer roll, reverse roll, and/or cast coating means,as well as any combination of the same.

The coated substrate may be dried in a drying section. Any drying meanscommonly known in the art of papermaking and/or coatings may beutilized. The drying section may include and contain IR, air impingementdryers and/or steam heated drying cans, or other drying means andmechanisms known in the coating art.

The coated substrate may be finished according to any finishing meanscommonly known in the art of papermaking. Examples of such finishingmeans, including one or more finishing stations, include gloss calendar,soft nip calendar, and/or extended nip calendar.

These above-mentioned methods of making the composition, particle,and/or paper substrate of the present invention may be added to anyconventional papermaking processes, as well as converting processes,including abrading, sanding, slitting, scoring, perforating, sparking,calendaring, sheet finishing, converting, coating, laminating, printing,etc. Preferred conventional processes include those tailored to producepaper substrates capable to be utilized as coated and/or uncoated paperproducts, board, and/or substrates.

The substrate may also include other conventional additives such as, forexample, starch, mineral and polymeric fillers, sizing agents, retentionaids, and strengthening polymers. Among the fillers that may be used areorganic and inorganic pigments such as, by way of example, minerals suchas calcium carbonate, kaolin, and talc and expanded and expandablemicrospheres. Other conventional additives include, but are notrestricted to, wet strength resins, internal sizes, dry strength resins,alum, fillers, pigments and dyes.

The expandable microsphere, composition, particle and/or paper substrateof the present invention may be utilized in any and all end usescommonly known in the art for using paper and/or paperboard substrates.Such end uses include the production of paper and/or paperboardpackaging and/or articles, including those requiring high and low basisweights in the respective substrates, which can range from envelopes andforms to folding carton, respectively. Further, the end product, articleand/or package may have multiple paper substrate layers, such ascorrugated structures, where at least one layer contains the expandablemicrosphere, composition, particle and/or paper substrate of the presentinvention.

In one embodiment, the article contains a plurality of paper substrateswhere any and/or all may comprise the expandable microsphere,composition, particle and/or paper substrate of the present invention.

In this specific embodiment, the expandable microsphere, composition,and/or particle are means for bulking paper articles and substrates.However, in this embodiment, any bulking means can be utilized, whilethe expandable microsphere, composition, particle and/or paper substrateof the present invention is the preferred bulking means. Further,multiple bulking means may be used in the article/package/substrate ofthe present invention.

Examples of other alternative bulking means may be, but is not limitedto, surfactants, Reactopaque, pre-expanded spheres, BCTMP (bleachedchemi-thermomechanical pulp), microfinishing, and multiply constructionfor creating an I-Beam structure in a paper or paper board substrate.Such bulking means may, when incorporated or applied to a papersubstrate, provide adequate print quality, caliper, basis weight, etc inthe absence harsh calendaring conditions (i.e. pressure at a single nipand/or less nips per calendaring means), yet allow an article to containa paper substrate having the below physical specifications andperformance characteristics.

The article according to this embodiment of present invention maycontain a bulking means ranging from 0.01 to 20, preferably from 0.5 to10, lb per ton of finished product when such bulking means is anadditive. The bulking means may be present at 0.01, 0.05, 0.1, 0.25,0.5, 0.75, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, and 20 lb per ton of finished product whensuch bulking means is an additive

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention at a caliper ranging from 3.5 to 8 mil, morepreferably from 4.2 to 6.0 mil, and most preferably from 4.9 to 5.2 mil.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention at a basis weight of from 12 to 30 lb per 1300square feet, preferably from 16 to 24 lb per 1300 square feet, mostpreferably from 16 to 22 lb per 1300 square feet.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention at a density of from 3.0 to 7.0, morepreferably 3.5 to 5.0, most preferably from 3.75 to 4.25 lb/1300 sq. ft.per 0.001 inch thickness.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention at a MD Gurley Stiffness of less than or equalto 500 msf, preferably from 150 to 500 msf, more preferably from 225 to325 msf. The MD Gurley Stiffness must be sufficient enough toaccommodate standard converting means, preferable converting means arethose commonly known in the art of making envelopes and forms.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention at a CD Gurley Stiffness of less than or equalto 250 msf, preferably from 50 to 250 msf, more preferably from 100 to200 msf. The CD Gurley Stiffness must be sufficient enough toaccommodate standard converting means, preferable converting means arethose commonly known in the art of making envelopes and forms.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may contain the paper substrateof the present invention having a Sheffield Smoothness of less than 350SU, preferably from 150 to 300 SU, most preferably from 175 to 275 SU.

When the article is an envelope and/or forms, the article according tothis embodiment of the present invention may be multilayered and containat least one layer containing the expandable microsphere, composition,particle and/or paper substrate of the present invention where the layerhas a width of from 1 to 15 inches and a length from 1 to 15 inches. Thewidth may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15inches, including any and all ranges and subranges therein. The lengthmay be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 inches,including any and all ranges and subranges therein.

The article according to the present invention may contain multiplelayers containing the expandable microsphere, composition, particleand/or paper substrate of the present invention which may or may not becontinuous.

Examples of the article according to the present invention may be anenvelope of any standard size and shape generally known in the envelopeindustry. Further, the article may be an envelope containing a pluralityof forms. The envelope of the present invention preferably contains apaper substrate having bulking means, preferable bulking means being theexpandable microsphere, composition, particle of the present invention.

Preferably, the article according to the present invention contains aplurality of forms made of the paper substrate having bulking means,preferable bulking means being the expandable microsphere, composition,particle of the present invention.

Most preferably the article is an envelope and a plurality of forms madeof the paper substrate having bulking means, preferable bulking meansbeing the expandable microsphere, composition, particle of the presentinvention.

It is especially preferable that the article of the present inventioncontain a plurality of forms that is a greater number by at least 1 formthan an article that does not contain a substrate having the abovementioned bulking means applied thereto. The article of the presentinvention has at least one layer (continuous or discontinuous)containing a substrate having the above mentioned bulking means appliedthereto. The most preferred bulking means is that of the expandablemicrosphere, composition, and/or particle applied thereto the substratecontained by the at least one layer of the article. Further, a layer ofthe article may be a form.

The package of the present invention weighs, on average, equal to orless than 1 ounce, preferably less than one ounce. The package of thepresent invention has one or a plurality of layers and has a weightwhose difference from 1 ounce is an absolute value that is more thanthat of a conventional package having the same number of layers.Accordingly, more layers may be incorporated into the package of thepresent invention than that of a conventional package, while maintaininga total weight of the package that is less than 1 ounce.

The package of the present invention weighs, on average, equal to orless than 1 ounce, preferably less than one ounce. The package of thepresent invention has one or a plurality of layers and has a weightwhose difference from 100 ounces is an absolute value that is more thanthat of a conventional package having the same number of layers.Accordingly, more layers may be incorporated into the package of thepresent invention than that of a conventional package, while maintaininga total weight of the package that is less than 1 ounce.

The present invention is explained in more detail with the aid of thefollowing embodiment example which is not intended to limit the scope ofthe present invention in any manner.

EXAMPLES Example 1 Coated Paper Substrate Containing ExpandableMicrospheres

A coated paper substrate useful, for example, as folding carton isproduced utilizing normal papermaking processes. The paper substrate wascalendared under a pressure of 10 psi and then a conventional coatingwas applied thereto using conventional coating means. After applicationof the coating layer thereto the substrate, print mottle measurements(both visual and by a much more sensitive and objective standard(Scanning) were taken. The relationship between data from this 2^(nd)Cyan scanner mottle system can be correlated to subjective visualperception (using the zero-to-ten guideline) or can be transformed intoequivalent mottle values as measured with a Tobias mottle tester fromTobias Associates using the following equation:

Tobias=Scanner Mottle*8.8+188

The methods of describing the procedures and details of setting up ofthe above-mentioned equation can be found in U.S. patent applicationSer. No. 10/945,306, filed Sep. 20, 2004, which is hereby incorporated,in its entirety, herein by reference. Then, in subsequent experiments,expandable microspheres were incorporated into the above conventionalprocess so as to produce papers having 1 wt % and 2 wt % expandablemicrospheres based on the total weight of the substrate. Two sets ofexperiments were performed utilizing calendar pressure means equal to 10and 20 psi, respectively. Results are reported in Table 1 for each.

The results in Table 1 clearly demonstrate that those substratescontaining expandable microspheres, when coated, provide a markedimprovement in print mottle as measured by the 2^(nd) Cyan scannermottle system.

Example 2 Further Coated Paper Substrates Containing ExpandableMicrospheres

A coated paper substrate useful, for example, as folding carton isproduced utilizing normal papermaking processes. After application ofthe coating layer thereto the substrate, print mottle measurements (bothvisual and by a much more sensitive and objective standard (Scanning))as well as other characteristics were taken (Reported in Table 2). Then,in subsequent experiments, expandable microspheres were incorporatedinto the above conventional process in amounts of 10, 5, 2, and 1 lb/tonso as to produce papers containing expandable microspheres. Results arereported in Table 2 for each. Further, FIG. 1 shows 2^(nd) Cyan scannermottle as a function of the amount of expandable microspheres added tothe papermaking process. Controls 1 and 2 had no expandable microspheresadded to the papermaking processes.

TABLE 1 Expandable Micro- 2nd cyan 6th Cyan Print Sample Calendarspheres Impression Print Approx. Caliper Mottle Mottle CodeIdentification Pressure (wt %) Setting Order Caliper at Press ScannerVisual Scanner Visual Texture Comments 01 12A Low pli 10 psi 1% 10-pt20-5 20.2 20.0 9.1 4.0 4.4 1.5 4.0 02 12A High pli 25 psi 1% 20-pt 20-218.8 20.0 8.3 4.0 4.8 2.0 4.0 03 11A Low pli 10 psi 2% 22-pt 22-3 21.621.5 7.6 5.0 4.0 2.0 4.0 04 11A High pli 25 psi 2% 22-pt 22-2 20.7 21.05.7 4.0 4.9 2.0 4.0 05 10C Low pli 10 psi 0% 20-pt 20-3 18.8 20.0 10.15.0 4.7 2.0 4.0 Trial Control 06 10C High pli 25 psi 0% 20-pt 20-4 18.320.0 9.9 5.0 5.3 2.0 4.0 Trial Control Print Mottle Scanner Print MottleVisual Print Mottle and Texture Rating Scanner mottle in a 1″ × 12″ (5 ×5 cm) without aqueous overprint coating 0.0-3.9 1.0-1.9 = Excellent,above the market norm on a 0.0 (excellent) to 10.0 scale. Visual mottlerates the worst mottle 4.0-5.9 2.0-2.9 = Good, market norm in a 3″ × 16″(15 × 40 cm) area, most with overprint coating. 6.0-7.9 3.0-3.9 = Fair,below market norm Overprint coating may make scanner mottle worse byabout 1.0 8.0-9.9 4.0-4.9 = Poor, possible rejection depending on mostsheets. Texture is rated 1.0 to 5.0 in KCMY overprint. upon job beingprinted 10.0+ 5.0+ = Rejectable

TABLE 2 Control 1 Trial 1 Trial 1 Control 2 Trial 2 Trial 2 (Pre-Trial)(5 lbs/ton) (10 lbs/ton) (Pre-Trial) (1 lb/ton) (2 lb/ton) Expanc

0 5 10 0 1 2 Dosage (lb/ton) Base Weight 255 237.4 225.6 255.1 251.2 247Ca

per 23.8 24.1 23.7 24.0 23.8 24.0 She

 (WS) 27.4 9.2 9 22.7 21.5 13.0 PPS10 1.61 1.5 1.55 1.47 1.48 1.42 G

 Stiffness 325 284 249 338 309 309 Internal Bond

0 72.7 68 74 76 81 Print 

 (2^(nd) 2.6 2.17 2.1 3.67 2.87 2.7 Cyan) Base Weight    6.9 11.5 1.533.18 Reduction (%)

indicates data missing or illegible when filed

Polyethylenimine (PEI) Adsorption on Microspheres * Expancel ®microsphere as 40% aqueous slurries * Slurries added dropwise to 6 wt %PEI (M_(n) = 10,000, M_(w) = 25,000 g/mol) solutions * Vigorous stirringcontinued for 2 hrs * Samples washed with 2 L DI H₂O each, then driedusing vacuum filtration Expancel ® Sample 820 820 642 SLU 40 SLU 80 SLX80 Adsorption Conditions Amount of 40% Slurry 7.5 g 7.5 g 7.5 g AmountPEI (6%) Solution  48 g  48 g  48 g g dry Particles:g dry PEI 1:1 1:11:1 Expansion Properties T o.e. (°C.) 82 83 90 T o.s. (°C.) 140 125 132V exp (80° C.) (mL) 1.2 2.3 1.4 V exp (100° C.)(mL) ~75 ~50 ~65 *Expansion properties were not substantially affected by the adsorptionof PEI

Surface Charge Reversal Through Post-Aluminization Modified process tocover standard expandable particles with layer of cationic colloidalalumina (resulting in reversal of anionic surface charge): Preparesuspension of colloidal alumina 28% solids, pH = 4.5) Slowly add treatedparticles (40 wt % slurry) to alumina suspension during vigorousstirring to keep particles dispersed; continue mixing for 1 hr Washparticles with large volume of water and dry using vacuum filtration To.e. Expansion (° C.) T o.s. (° C.) (mL) Zeta Potential (mV) Treated 75101 7.8 avg = −70.0; SD-1.5 Aluminized 78 106 8.4 avg = +30.2; SD = 2.4Cationic surface charge was effectively produced

Experiments

Charge Modification of X-100

-   -   Adsorption of PEI    -   Visual observation of particles in slurry in the charge reversal        process    -   Measurement of Adsorbed PEI    -   Measurement of Zeta Potential

Retention Analysis

-   -   Britt Jar    -   Measurement of Unretained X-100 (Isobutane in GC)

Bulk Development

-   -   Williams handsheets with control and charge modified particles

Measurement of System Charge

-   -   Quantification of the effect of unadsorbed PEI and charge        modified X-100 on the headbox charge

Experiments

Charge Modification of X-100

-   -   Materials        -   Low MW PEI (25,000) & High MW PEI (750,000)        -   642 SLX80        -   Ratio of X-100/PEI varied from 4 to 40    -   Methods        -   Mixing time varied 1-4 h        -   Visual observations for incompatibility        -   PEI, X-100 mixture centrifuged and washed to remove excess            PEI (See FIG. 6)

Adsorption Conditions

Condi- X-100/EPI Mixing tion PEI Ratio Time (h) Observation 1 NA NA 2ALow MW 4.00 1 Smooth Mixture 2B Low MW 4.00 4 Smooth Mixture 3A Low MW10.00 1 Initial floc became smooth mixture 3B Low MW 10.00 4 Initialfloc became smooth mixture 4A Low MW 20.00 1 Initial floc became smoothmixture 4B Low MW 20.00 4 Initial floc - remained flocculated 9 High MW40.00 1 Smooth Mixture

As used throughout, ranges are used as a short hand for describing eachand every value that is within the range, including all subrangestherein.

Numerous modifications and variations on the present invention arepossible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the accompanying claims, theinvention may be practiced otherwise than as specifically describedherein.

All of the references, as well as their cited references, cited hereinare hereby incorporated by reference with respect to relative portionsrelated to the subject matter of the present invention and all of itsembodiments

What is claimed is:
 1. A composition, comprising at least one expandablemicrosphere and at least one ionic compound, wherein said compositionhas a zeta potential that is greater than or equal to zero mV at a pH ofabout 9.0 or less at an ionic strength of from 10⁻⁶ M to 0.1M.
 2. Thecomposition according to claim 1, wherein said zeta potential is greaterthan zero mV.
 3. The composition according to claim 1, wherein said zetapotential ranges from greater than zero to +150 mV.
 4. The compositionaccording to claim 1, wherein said zeta potential ranges from greaterthan +20 to +130 mV.
 5. The composition according to claim 1, whereinsaid ionic compound is at least one compound selected from the groupconsisting of an organic and inorganic ionic compound.
 6. Thecomposition according to claim 1, wherein said ionic compound is atleast one polyorganic compound.
 7. The composition according to claim 1,wherein said ionic compound is at least one polyamine compound.
 8. Thecomposition according to claim 1, wherein said ionic compound iscrosslinked, branched, or combinations thereof.
 9. The compositionaccording to claim 1, wherein said ionic compound is at least onepolyethyleneimine compound.
 10. The composition according to claim 1,wherein said ionic compound is at least one polyethyleneimine compoundhaving a molecular weight of at least 600 weight average molecularweight.
 11. The composition according to claim 1, wherein said ioniccompound is at least one polyethyleneimine compound having a molecularweight of from 600 to 40,000 weight average molecular weight.
 12. Thecomposition according to claim 1, wherein said ionic compound iscationic.
 13. The composition according to claim 1, wherein said ioniccompound comprises at least one member selected from the groupconsisting of alumina and silica.
 14. The composition according to claim1, wherein said ionic compound comprises a colloid comprising at leastone member selected from the group consisting of silica, alumina, tinoxide, zirconia, antimony oxide, iron oxide, and rare earth metaloxides.
 15. The composition according to claim 1, wherein said ioniccompound comprises a sol comprising at least one member selected fromthe group consisting of silica, alumina, tin oxide, zirconia, antimonyoxide, iron oxide, and rare earth metal oxides.
 16. The compositionaccording to claim 1, wherein the composition is a particle.
 17. Thecomposition according to claim 16, wherein an outside surface of the atleast one expandable microsphere is bound to the ionic compound.
 18. Thecomposition according to claim 16, wherein an outside surface of the atleast one expandable microsphere is non-covalently bound to the ioniccompound.
 19. The particle according to claim 16, wherein the outsidesurface of at least one expandable microsphere is anionic.
 20. Theparticle according to claim 16, wherein the ionic compound is cationic.20. A method of making the composition according to claim 1, comprisingcontacting the at least one expandable microsphere with the at least oneionic compound to form a mixture.
 21. The method according to claim 20,further comprising centrifuging the mixture to form a first phasecomprising at least one ionic compound and a second phase comprising theparticle.
 22. A method of making the composition according to claim 1,comprising adsorbing at least one ionic compound to at least oneexpandable microsphere
 23. The composition according to claim 1, furthercomprising a plurality of cellulose fibers.
 24. The compositionaccording to claim 23, wherein an outside surface of the at least oneexpandable microsphere is bound to the ionic compound.
 25. Thecomposition according to claim 23, wherein an outside surface of the atleast one expandable microsphere is non-covalently bound to the ioniccompound.
 26. A method of making the composition according to claim 23,comprising contacting the at least one expandable microsphere with theat least one ionic compound to form a particle, and contacting saidparticle with said plurality of cellulose fibers.
 27. A method of makingthe composition according to claim 23, comprising contacting the atleast one expandable microsphere with the at least one ionic compound toform a particle; and injecting the particle into a solution comprising aplurality of cellulose fibers.
 28. A paper or paperboard substrate,comprising a plurality of cellulose fibers; from 0.1 to 5 wt % of aplurality of expandable microspheres; wherein the substrate has aSheffield Smoothness of less than 250 SU as measured by TAPPI testmethod T 538 om-1; and a scanning 2^(nd) cyan print mottle of not morethan
 6. 29. The substrate according to claim 28, wherein an outsidesurface of the expandable microspheres are bound to an ionic compound.30. The substrate according to claim 28, comprising from 0.1 to 3 wt %of a plurality of expandable microspheres.
 31. The substrate accordingto claim 28, comprising from 0.1 to 2 wt % of a plurality of expandablemicrospheres.
 32. The substrate according to claim 28, furthercomprising at least one coating layer.
 33. The substrate according toclaim 28, wherein the coating layer comprises at least one top coat andat least one base coat.
 34. The substrate according to claim 28, whereinthe Sheffield Smoothness is less than 250 SU and the scanning printmottle is less than 6 after calendaring said substrate, as measured byTAPPI test method T 538 om-1.
 35. The substrate according to claim 28,wherein the substrate has a Parker Print Surface Smoothness of fromabout 1.0 to 0.5 as measured by TAPPI test method T 555 om-99
 36. Anarticle, comprising the substrate according to claim
 28. 37. The articleaccording to claim 33, wherein the article is a folding carton.
 38. Anarticle, comprising at least one paper or paperboard substrate whereinas least one substrate comprises a web of cellulose fibers and a bulkingagent; wherein the article weighs equal to or less than one ounce; andwherein the article has a weight whose difference from 1 ounce is anabsolute value that is more than that of a conventional package havingthe same number of layers.